The use of carrier-bound reactive species for analytical purposes is known. Rebek et al, JACS 97:2 (1975) page 454 and Rebek et al, Tetrahedron vol. 35, pages 723-737, 1979 described a three phase test for the detection of intermediates. The test involves the generation of a reactive intermediate from an insoluble polymeric precursor and its detection by trapping on a second solid phase. This method is especially useful for the detection of intermediates in nucleophilic catalysis. The same principle was applied by Rebek to reactions involving metaphosphates, cyclobutadiene and in phosphate transfer reactions. Except for certain specific acylation reactions, none of the three-phase reactions of Rebek disclose regenerable intermediates. Although similar in principle to the reaction carried out in the device of the present invention, Rebek et al describes an analytical reaction with minimum quantities of reactants without envisaging applicability for synthetic purposes. Moreover, in the case of Rebek, the two polymers were mixed together or were separated by sintered glass frit and the reactive intermediate formed was transferred from one polymer to the other. This system does not permit monitoring and automation of the reaction.